Continuous tube for forming bags containing fruit and vegetable products

ABSTRACT

The invention relates to a continuous tube for forming bags containing fruit and vegetable products, having at least one pair of mesh strips ( 1 - 1′ ), each of the mesh strips ( 1 - 1′ ) being located once folded such that the edges defined by the mentioned folds ( 2 - 2′ ) are opposite one another and separated a certain distance S; each mesh strip ( 1 - 1 ) having a fold at both ends, end portions ( 3 - 4; 3′ - 4′ ) having width A being defined, B being the distance between the fold ( 2 - 2′ ) and the free ends ( 5 - 6; 5′ - 6′ ) of a single strip; a pair of laminar strips ( 7 - 7′ ) having a width C equivalent to at least two times the distance B plus the distance S, and at least four reinforcing strips ( 8 - 9; 8′ - 9′ ) having a width less than the width A of the end portions ( 3 - 4; 3′ - 4′ ) of each of the mesh strips ( 1 - 1′ ).

FIELD AND OBJECT OF THE INVENTION

The invention is comprised within the field of packaged fruit and vegetable products, such as for example potatoes or oranges, and more specifically it relates to a continuous tube for forming bags containing the mentioned fruit and vegetable products, which is formed from mesh strips, laminar strips and reinforcing strips which, once joined to one another, define the continuous tube.

STATE OF THE ART

Different types of bags intended to contain fruit and vegetable products such as oranges, lemons, potatoes etc. which are normally formed from a continuous extruded mesh tube, which is filled with the mentioned products and is subsequently closed in the packaging process, are already known in the market.

The tube obtained by means of the process described in patent number 200102600 is formed from four longitudinal strips, two side mesh strips, and two plastic laminar strips, arranged in alternating positions being partially overlapped, the laminar strips being specifically located outwardly from the side mesh strips. The laminar strips and the side mesh strips are joined to one another by means of heat-welding; this manufacturing process has the following drawbacks:

-   -   the heat applied for the mentioned joining makes the laminar         strip wrinkle on occasions and the graphic prints be deformed         and the letters unreadable.     -   this process is limited to the use of certain materials for the         mesh strips and the laminar strips, because in order for the         materials to be securely joined to one another, it is necessary         for them to both have similar melting points, so joining         materials with different natures and melting points is not         allowed, for example: polypropylene, polyethylene, paper, etc.     -   the tube production rate is fairly slow given that it is         necessary to wait until the melted material cools in order to be         able to handle the tube without deformations occurring.

The objective of the invention is to solve the problems set forth, joining the laminar strips and the side mesh strips to one another by means of simple gluing instead of by means of heat welding, for which purpose it is necessary to introduce additional strips located on the inner face of the free ends of the side mesh strips, the main purpose of which is to reinforce the joint between the laminar strips and the side mesh strips. Furthermore respective folds are made on the side mesh strips from which the tube is formed, which folds are made towards the inside of the tube and define two edges located close and opposite to one another, and a partial fold is additionally made on the ends of the sides of the tube.

This objective is achieved by means of the invention as it is defined in claim 1; preferred embodiments of the invention are defined in the dependent claims.

DESCRIPTION OF THE INVENTION

The present invention relates to a continuous tube for forming bags containing fruit and vegetable products, comprising at least a pair of mesh strips, a pair of laminar strips and at least four reinforcing strips.

The mesh strips are each preformed with a central fold made on the smaller dimension of each mesh strip following its larger dimension, each of the mesh strips being located once folded such that the edges defined by the mentioned folds are opposite one another and separated a certain distance S, each mesh strip having a fold at both ends, end portions having width A being defined, B being the distance between the fold and the free ends of a single strip and the upper end portions of each of the strips being located in a coplanar manner and the lower end portions thereof in an equally coplanar manner according to two parallel planes separated a distance W.

The laminar strips have a width C equivalent to at least two times the distance B plus the distance S, each of the laminar strips being respectively located outwardly from each pair of coplanar end portions and of said mesh strips.

The at least four reinforcing strips in turn have a width less than the width A of the end portions of each of the mesh strips, said reinforcing strips being arranged in a substantially parallel manner and coinciding with said end portions at the free outer part not covered by the respective laminar strips, said reinforcing strips being joined to the mesh strips and in turn to the laminar strips.

Thus as a result of the configuration of the mesh strips, which are folded, and of the relative positioning of such mesh strips, the reinforcing strips can be easily introduced due to the fact that such reinforcing strips will always be outside the mentioned mesh strips, preventing having to introduce them inside the space delimited by the mesh and laminar strips and therefore making the production rate increase considerably. Furthermore as a result of the mentioned folds of the mesh strips, considerable space can be saved in the mesh strip reels and working with very small accordions is allowed, even in those which the vertex does not reach the central longitudinal axis of the tube, thus creating bags with a very small capacity, such as for packaging garlic, for example.

One final advantage achieved as a result of previously folding the mesh strips forming an inverted accordion is that it ensures a perfect fit for joining the bottom and the mouth of the bag due to the fact that since the mesh strips in the folded position were wound for a significant amount of time, the shape is reactivated due to a memory effect of the plastic.

In addition, providing the mentioned mesh strips with a fold at each of its ends to define end portions facilitates the process for joining the mesh strips and the laminar strips due to the fact that since the upper end portions of the strips are located on a single plane just as the lower end portions are and said planes are parallel to the corresponding laminar strips, a closer, stronger and more secure joint between both types of strips and a better finishing thereof is achieved.

Finally reinforcing strips are used which are placed in a substantially parallel and coinciding manner with said end portions, at the free outer part not covered by the respective laminar strips, in order to define a sandwich-type arrangement at each of the four joints which are defined in the continuous tube, formed by three layers: a first layer formed by the end of the corresponding laminar strip, a middle layer formed by the corresponding end portion of the mesh strip and a third layer formed by the reinforcing strip. Said arrangement makes the bags formed from the tube defined in the present invention stronger and causes greater verticality or rigidness of the tube, making the storage of the bags full of products safer and more stable.

In addition, placing the reinforcing strips so as to coincide with the handgrip which each bag incorporates makes fixing said handles more solid than if they were only joined to the laminar strips, thus preventing detachments of said handles during the transport of the bags, and preventing the transported product from being damaged.

As can be observed in this first aspect of the invention the use of two mesh strips is considered; in this case the mesh strips used will normally be made of extruded mesh since due to their high strength they allow using two mesh strips instead of a continuous mesh tube.

In the event of using woven mesh instead of extruded mesh, it is necessary to have a complete mesh tube since the strength of this type of mesh is much more limited than in the case of extruded mesh. For such reason and in a second aspect of the invention, a continuous tube has been considered which is characterized in that the coplanar upper end portions, each of them corresponding to a mesh strip, are joined to one another forming a continuous upper base, and in that the coplanar lower end portions, each of them corresponding to a mesh strip, are joined to one another forming a continuous lower base, a closed mesh tube having two side folds like an accordion being defined, respective laminar strips being arranged outwardly from the upper and lower bases of said mesh tube and four reinforcing strips located on the end portions, at the free outer part of each mesh tube not covered by the laminar strips, covering the width A of said end portions.

The reinforcing strips are joined with the assembly formed by the mesh strips and the laminar strips by means of heat-sealable substances.

It is thus achieved that there are no deformations in the laminar strips since they do not have to be heated in order to be joined to the mesh strips, therefore there are no deformations in the texts printed on the mentioned laminar strips and the texts of both laminar strips are more easily matched up. Furthermore, different materials can be used in manufacturing the tube, such as paper with polypropylene or polyethylene, since most materials withstand low temperatures which the joints are subjected to during the heat-welding step.

Since the materials do not have to be heated as much to be joined to one another, barely any time has to pass before they are cooled in order to be able to handle them, whereby considerably increasing the tube production rate.

DESCRIPTION OF THE DRAWINGS

A series of drawings will be very briefly described below which aid in better understand the invention and which are specifically related to an embodiment of said invention, presented as illustrative and non-limiting examples thereof.

FIG. 1 shows a sectional view of the continuous tube object of the present invention in a first embodiment thereof for the case of the extruded mesh strips.

FIG. 2 schematically shows a plan view and a side view of the manufacturing installation for the continuous tube corresponding to the first embodiment of the invention.

FIG. 3 shows a sectional view of the continuous tube object of the present invention in a second embodiment thereof for the case of a complete woven mesh tube.

FIG. 4 schematically shows a plan view and a side view of the manufacturing installation for the continuous tube corresponding to the second embodiment of the invention.

DESCRIPTION OF EMBODIMENTS OF THE INVENTION

The continuous tube for forming bags containing fruit and vegetable products object of the present invention in a first embodiment thereof, as can be seen in FIG. 1, comprises at least a pair of already folded mesh strips 1-1′ which can come from a reel (not depicted), each having a central fold 2-2′ made on the smaller dimension of each mesh strip following its larger dimension. Each of the strips can be obtained from previously splitting a complete extruded mesh tube into two equal parts, each of which will form each of the mesh strips 1-1′.

Once each of the mesh strips 1-1′ is folded, they are located such that the edges defined by the mentioned folds 2-2′ are opposite one another and separated a certain distance S, B being the distance between the fold 2-2′ and the free ends 5-6; 5′-6′ of a single strip.

Near each of its ends, each mesh strip 1-1′ has a fold, end portions 3-4; 3′-4′ having a width A being defined by the fold lines in each case.

The upper end portions 3-3′ of each of the strips are located in a coplanar manner and the lower end portions 4-4′ thereof in an equally coplanar manner, both planes in which the mentioned portions are located are separated a certain distance W, which is defined depending on the final dimensions to be achieved from the bags or containers for the fruit and vegetable products to be packaged.

Laminar strips 7 and 7′ are respectively located externally on the pairs of coplanar end portions 3-3′ and 4-4′, the width of the mentioned laminar strips being equivalent at least to the sum of two times the distance B plus the separation distance S between the folds 2-2′ of the mesh strips 1-1′.

The overlapping between the laminar strips 7-7′ and the mesh strips 1-1′ defines the continuous tube, both types of strips being joined to one another only through the end portions 3-3′ and 4-4′ by simply applying an adhesive, apply heat and pressure to the joint as will be detailed below.

Reinforcing strips 8-9 and 8′-9,′ the width of which is less than the width A of the mentioned end portions, are arranged on the end portions 3-3′ and 4-4′, at the free outer part not covered by the respective laminar strips 7-7′; such reinforcing strips are placed in a substantially parallel manner and coinciding with said end portions 3-4 and 3′-4′.

As relates to the manufacturing installation for the improved tube, as is shown in FIG. 2, it starts from mesh strips 1-1′ which are opened in respective plates 11-11′ that are integrally joined to the mount of the installation, each of the mesh strips being located inwardly from the mentioned plates 11-11′ and surrounding these plates such that the edges defined by the folds 2-2′ of the mesh strips are opposite one another.

The reinforcing strips 8-9 in the initial area of the installation are in turn located respectively one above and one below the plate 11, whereas the other two reinforcing strips 8′-9′ are located one above and the other below the plate 11′.

Respective rollers 12-12′ are subsequently located one above and one below the mount, at a certain distance therefrom, through which the laminar strips 7 and 7′ respectively pass; at this moment several adhesive glue applicators, two of them 13 located above the tube and two of them 13′ below such tube, apply glue on the inner face of the laminar strips 7 and 7′ respectively.

The strips, which will first run outside the mesh strips, as is seen in FIG. 2, then pass, as a result of respective slits 14-14′ made on the plates 11 and 11′ respectively and depicted in the figure by means of a bend in the path of the mentioned strips, to be located just below the innermost face of the mesh strips.

Each of the laminar strips 7-7′ are driven towards pressure rollers 15-15′ respectively, by means of intermediate rollers 16-16′ tensing said laminar strips; said pressure rollers 15-15′ press each laminar strip, the inner face of which is previously impregnated with glue through the glue applicators, against the corresponding mesh strip 1-1′ and in turn against the reinforcing strips 8-9; 8′-9′ located below the end portions 3-3′ and 4-4′ of each laminar mesh, achieving formation of the joint, reinforced by the mentioned strips, between the laminar strips and the mentioned end portions of the mesh strips, defining a very strong closed tube, the sides of which are made of extruded mesh and the front-ends are made of a laminar strip which can be printed for commercial and informative purposes.

The joint achieved between the laminar strips 7-7′ and the mesh strips 1-1′ is very strong due to the fact that the mesh strip is located in an intermediate position between the corresponding laminar strip and the reinforcing strip and due to its mesh structure, the glue deposited on the laminar face passes through the gaps of the mesh strips and is able to reach the reinforcing strip, making it so that in a single pressure step, by means of pressure rollers 11-11′, the three layers are joined to one another, defining a sandwich-type structure in which the mesh strip layer is retained between the corresponding laminar strip layer and the layer formed by the reinforcing strip.

In a second embodiment of the invention, depicted in FIG. 3, the mesh used will be woven and instead of two mesh strips a closed or complete mesh tube will be used; for this purpose the coplanar upper end portions 3-3′, each of them corresponding to a mesh strip 1-1′, will be joined to one another forming a continuous upper base 10, and in turn the coplanar lower end portions 4-4′, each of them corresponding to a mesh strip 1-1′, will be joined to one another forming a continuous lower base 10′; said continuity defines a closed mesh tube, which, as in the case of extorted mesh, has two side folds 2-2′ like an accordion, respective laminar strips 7-7′ being arranged, as in the previous case, outwardly from the upper 10 and lower 10′ bases of said mesh tube.

The main reason for using a complete mesh tube in the case of woven meshes is that the breaking strength thereof is considerably less than in extruded meshes, whereby it is necessary to conserve the continuity of the initial tube, being reinforced in two of its faces by joining the laminar strips, and being further reinforced by adding reinforcing strips, making the bags obtained from the tube very strong.

For the second embodiment of the invention an installation slightly different from that used in the previous case will be used. Given that the installation starts with a continuous mesh material, it is necessary to define the shape of the double accordion determined by the folds 2-2′ from the start of the installation; for this purpose it is necessary to use a pair of initial plates 17-17′ against which respective plates 18-18′ are placed perpendicular to each of the plates 17-17′ respectively, and respective tensing pairs, formed as bars 19-20 and 19′-20′, start from such plates 18-18′. The plates 17, 18 and the bars 19 and 20 are joined to one another and define an upper body for securing the tube which is responsible for securing the upper base 10 of the mesh tube, whereas the plates 17′, 18′ and the bars 19′ and 20′ are joined to one another and define a lower body for securing the tube which is responsible for securing the lower base 10′ of the mesh tube. Both upper and lower bodies are separated a certain distance for the purpose of allowing the mesh tube to run between them.

Third coplanar plates 21 and 22 separated from one another a certain distance coinciding with the separation distance S between the folds 2-2′ of the mesh are arranged in an intermediate position between the mentioned upper and lower bodies for securing the tube in order to define the folds 2-2′.

The installation with thus have means for being able to take the tube from a shrunken state to a tensed or stretched state forcing the tube to pass outside the bars 19-20 and 19′-20′ as is shown in FIG. 4. 

1. A continuous tube for forming bags containing fruit and vegetable products comprising: at least a pair of mesh strips, each preformed with a central fold made on the smaller dimension of each mesh strip following its larger dimension, each of the mesh strips being located once folded such that the edges defined by the mentioned folds are opposite one another and separated a certain distance S, each mesh strip having a fold at both ends, end portions having width A being defined, B being the distance between the fold and the free ends of a single strip and the upper end portions of each of the strips being located in a coplanar manner and the lower end portions thereof being located in an equally coplanar manner according to two parallel planes separated a distance W, a pair of laminar strips having a width C equivalent to at least two times the distance B plus the distance S, each of the laminar strips being respectively located outwardly from each pair of coplanar end portions and of said mesh strips, and at least four reinforcing strips having a width less than the width A of the end portions of each of the mesh strips, said reinforcing strips being arranged in a substantially parallel manner and coinciding with said end portions, at the free outer part not covered by the respective laminar strips, said reinforcing strips being joined to the mesh strips and in turn to the laminar strips.
 2. A continuous tube according to claim 1, wherein the coplanar upper end portions, each of them corresponding to a mesh strip, are joined to one another forming a continuous upper base, and in that the coplanar lower end portions, each of them corresponding to a mesh strip, are joined to one another forming a continuous lower base, a closed mesh tube having two side folds like an accordion being defined, respective laminar strips being arranged outwardly from the upper and lower bases of said mesh tube, and four reinforcing strips located on the end portions, at the free outer part of each mesh tube not covered by the laminar strips, covering the width A of said end portions.
 3. A continuous tube according to claim 1, the mesh strips are formed by extruded mesh.
 4. A continuous tube according to claim 2, wherein the mesh strips are formed by woven mesh.
 5. A continuous tube according to, claim 1, wherein the reinforcing strips are joined with the assembly formed by the mesh strips and the laminar strips by means of heat-sealable substances. 